To investigate if ERK activation is involved in prostate cancer CM-induced osteoclastogenesis, we cultured RANKL-primed RAW 264.7 osteoclast precursors untreated, treated with RANKL (50 ng/ml), or supplemented with 10% PC3 or LNCaP CM for 5–60 min. Here, TNFSF11 is linked to prostate cancer.